package org.apache.velocity.context;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */

import org.apache.velocity.app.event.EventCartridge;
import org.apache.velocity.runtime.resource.Resource;
import org.apache.velocity.util.introspection.IntrospectionCacheData;

import java.util.List;

/**
 * This adapter class is the container for all context types for internal use.
 * The AST now uses this class rather than the app-level Context interface to
 * allow flexibility in the future.
 * 
 * Currently, we have two context interfaces which must be supported :
 * <ul>
 * <li>Context : used for application/template data access
 * <li>InternalHousekeepingContext : used for internal housekeeping and caching
 * <li>InternalWrapperContext : used for getting root cache context and other
 * such.
 * <li>InternalEventContext : for event handling.
 * </ul>
 * 
 * This class implements the two interfaces to ensure that all methods are
 * supported. When adding to the interfaces, or adding more context
 * functionality, the interface is the primary definition, so alter that first
 * and then all classes as necessary. As of this writing, this would be the only
 * class affected by changes to InternalContext
 * 
 * This class ensures that an InternalContextBase is available for internal use.
 * If an application constructs their own Context-implementing object w/o
 * subclassing AbstractContext, it may be that support for InternalContext is
 * not available. Therefore, InternalContextAdapter will create an
 * InternalContextBase if necessary for this support. Note that if this is
 * necessary, internal information such as node-cache data will be lost from use
 * to use of the context. This may or may not be important, depending upon
 * application.
 * 
 * 
 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
 * @version $Id: InternalContextAdapterImpl.java 731266 2009-01-04 15:11:20Z
 *          byron $
 */
public final class InternalContextAdapterImpl implements InternalContextAdapter {
	/**
	 * the user data Context that we are wrapping
	 */
	Context context = null;

	/**
	 * the ICB we are wrapping. We may need to make one if the user data context
	 * implementation doesn't support one. The default AbstractContext-derived
	 * VelocityContext does, and it's recommended that people derive new
	 * contexts from AbstractContext rather than piecing things together
	 */
	InternalHousekeepingContext icb = null;

	/**
	 * The InternalEventContext that we are wrapping. If the context passed to
	 * us doesn't support it, no biggie. We don't make it for them - since its a
	 * user context thing, nothing gained by making one for them now
	 */
	InternalEventContext iec = null;

	/**
	 * CTOR takes a Context and wraps it, delegating all 'data' calls to it.
	 * 
	 * For support of internal contexts, it will create an InternalContextBase
	 * if need be.
	 * 
	 * @param c
	 */
	public InternalContextAdapterImpl(Context c) {
		context = c;

		if (!(c instanceof InternalHousekeepingContext)) {
			icb = new InternalContextBase();
		} else {
			icb = (InternalHousekeepingContext) context;
		}

		if (c instanceof InternalEventContext) {
			iec = (InternalEventContext) context;
		}
	}

	/* --- InternalHousekeepingContext interface methods --- */

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#pushCurrentTemplateName(java.lang.String)
	 */
	public void pushCurrentTemplateName(String s) {
		icb.pushCurrentTemplateName(s);
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#popCurrentTemplateName()
	 */
	public void popCurrentTemplateName() {
		icb.popCurrentTemplateName();
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#getCurrentTemplateName()
	 */
	public String getCurrentTemplateName() {
		return icb.getCurrentTemplateName();
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#getTemplateNameStack()
	 */
	public Object[] getTemplateNameStack() {
		return icb.getTemplateNameStack();
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#pushCurrentMacroName(java.lang.String)
	 * @since 1.6
	 */
	public void pushCurrentMacroName(String s) {
		icb.pushCurrentMacroName(s);
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#popCurrentMacroName()
	 * @since 1.6
	 */
	public void popCurrentMacroName() {
		icb.popCurrentMacroName();
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#getCurrentMacroName()
	 * @since 1.6
	 */
	public String getCurrentMacroName() {
		return icb.getCurrentMacroName();
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#getCurrentMacroCallDepth()
	 * @since 1.6
	 */
	public int getCurrentMacroCallDepth() {
		return icb.getCurrentMacroCallDepth();
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#getMacroNameStack()
	 * @since 1.6
	 */
	public Object[] getMacroNameStack() {
		return icb.getMacroNameStack();
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#icacheGet(java.lang.Object)
	 */
	public IntrospectionCacheData icacheGet(Object key) {
		return icb.icacheGet(key);
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#icachePut(java.lang.Object,
	 *      org.apache.velocity.util.introspection.IntrospectionCacheData)
	 */
	public void icachePut(Object key, IntrospectionCacheData o) {
		icb.icachePut(key, o);
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#setCurrentResource(org.apache.velocity.runtime.resource.Resource)
	 */
	public void setCurrentResource(Resource r) {
		icb.setCurrentResource(r);
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#getCurrentResource()
	 */
	public Resource getCurrentResource() {
		return icb.getCurrentResource();
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#setMacroLibraries(List)
	 * @since 1.6
	 */
	public void setMacroLibraries(List macroLibraries) {
		icb.setMacroLibraries(macroLibraries);
	}

	/**
	 * @see org.apache.velocity.context.InternalHousekeepingContext#getMacroLibraries()
	 * @since 1.6
	 */
	public List getMacroLibraries() {
		return icb.getMacroLibraries();
	}

	/* --- Context interface methods --- */

	/**
	 * @see org.apache.velocity.context.Context#put(java.lang.String,
	 *      java.lang.Object)
	 */
	public Object put(String key, Object value) {
		return context.put(key, value);
	}

	/**
	 * @see InternalWrapperContext#localPut(String, Object)
	 * @since 1.5
	 */
	public Object localPut(final String key, final Object value) {
		return put(key, value);
	}

	/**
	 * @see org.apache.velocity.context.Context#get(java.lang.String)
	 */
	public Object get(String key) {
		return context.get(key);
	}

	/**
	 * @see org.apache.velocity.context.Context#containsKey(java.lang.Object)
	 */
	public boolean containsKey(Object key) {
		return context.containsKey(key);
	}

	/**
	 * @see org.apache.velocity.context.Context#getKeys()
	 */
	public Object[] getKeys() {
		return context.getKeys();
	}

	/**
	 * @see org.apache.velocity.context.Context#remove(java.lang.Object)
	 */
	public Object remove(Object key) {
		return context.remove(key);
	}

	/* ---- InternalWrapperContext --- */

	/**
	 * returns the user data context that we are wrapping
	 * 
	 * @return The internal user data context.
	 */
	public Context getInternalUserContext() {
		return context;
	}

	/**
	 * Returns the base context that we are wrapping. Here, its this, but for
	 * other thing like VM related context contortions, it can be something else
	 * 
	 * @return The base context.
	 */
	public InternalContextAdapter getBaseContext() {
		return this;
	}

	/* ----- InternalEventContext ---- */

	/**
	 * @see org.apache.velocity.context.InternalEventContext#attachEventCartridge(org.apache.velocity.app.event.EventCartridge)
	 */
	public EventCartridge attachEventCartridge(EventCartridge ec) {
		if (iec != null) {
			return iec.attachEventCartridge(ec);
		}

		return null;
	}

	/**
	 * @see org.apache.velocity.context.InternalEventContext#getEventCartridge()
	 */
	public EventCartridge getEventCartridge() {
		if (iec != null) {
			return iec.getEventCartridge();
		}

		return null;
	}
}
